Armored Chondrules

Chuck,

Thank you for slicing up a few of my NWA 869s for me. Per our deal I’m sending half the slices back to you. You say you’re going to give them away to kids but you ought to keep that one with the armored chondrules to show around. I put it in a membrane box to keep it separate.

Armored chondrules aren’t rare but they still seem special. Maybe it’s the name. Armored. Sounds substantial. That shiny ring we see around sliced chondrules is a section through a metal-sulfide shell that more or less coats the chondrule. One explanation for how these came into being is that during chondrule formation metal-sulfide droplets, whatever their origin, separated from the silicate melt and gathered on the surface of solidifying chondrules – dubbed “expelled” coatings. Another suggestion is that MS vaporized during chondrule melting and then deposited on chondrule surfaces during cooling – “recondensed” coatings. [Summarized by Vogel et al. (2004) in MAPS.] Another scenario invokes impact mobilization of MS, fragmentation of the parent body and subsequent reaccretion – an impact and reaccumulation process. [Kojima et al. (2003) in Geochimica et Cosmochimica Acta.]

Here are some pictures.

– John

My first. CR2s weren’t cheap before the great desert bonanza took hold. But when Rob Elliott said those magic words, Armored Chondrules, I had to have it. $324 per gram. Give your NWA 869 a hug tonight. Acfer 209 CR2.

Years later I got this LL3 on eBay for about three bucks per gram. Neat stuff. Adrar Madet 002 LL3 S4, W2.

A bull’s eye. DaG 1040 CV3.

A metal shell with additional material around it. DaG 1040 CV3.

Same, with the addition of transmitted cross polarized light.

Incident light and transmitted XPL. NWA 801 CR2.

Shişr 033 CR2

There’s a lot going on here. Is that an armored bleb of metal?

Yes, and, not surprisingly, a layered bleb. Probably a CR2.

NWA 801 CR2, my favorite.

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About the Author

John Kashuba
John is a natural history enthusiast living in Oregon.
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